Vehicles monitor engine coolant temperature sensors for various purposes. One purpose is to detect a failure of the engine coolant temperature sensor. Generally, gasoline powered vehicles can determine coolant temperature as a function of fuel consumption because a specific quantity of fuel combusted by the engine generates a predictable amount of heat. This heat is then transferred to the coolant, which increases the temperature of the coolant by a known amount. Thus, in order to determine if the engine coolant temperature sensor is operating properly, the signal from an engine coolant temperature sensor can be compared to an expected engine coolant temperature corresponding to a known amount of gasoline that was used.
However, flex fuel vehicles may use ethanol and/or other types of fuel in addition to gasoline. Different types of fuels generate different amounts of heat compared to gasoline. Therefore, it may be difficult to monitor the engine coolant temperature sensor in flex fuel vehicles based on fuel consumption.